The current Center proposal represents a natural extension of our long-term efforts to investigate and to better understand the cognitive and neurobiological mechanisms underlying learning disabilities; it is both thematically and conceptually coherent with the previous Center grant themes and responsiveto the RFA. Each the proposed projects coalesces around the central themes: neurobiological mechanisms, effect of focused interventions, developmental course and outcome. Togther, these projects extend the studies of neurobiological mechanisms in reading and reading disability to focus on 1)how these neural systems respond in reading disabled and non reading-impaired children as reading fluency develops (Project I); 2) the relationship between attentional mechanisms and reading (Project II); and 3) changes in a brain neurotransmitter system, GABA, in children with reading disability and how this transmitter changes over development and in relation to sex hormones (Project V). We also integrate the understanding of neurobiological mechanisms and our interest in interventions to study the effect of an intervention on the developing neural systems for reading fluency (Project IV) and to examine how attention influences learning (Project II). In addition, we exploit the remarkable advances made in understanding the cognitive mechanisms underlying number processing to begin to examine neurobiological mechanisms in mathematics and mathematics disability (Project III). We continue our long-standing study of the developmental course and outcome of learning and attention disorders to examine adult outcome (Project VI). By providing an understanding at a fundamental level of the neural mechanisms underlying skilled and poor reading and mathematics and mathematics disability, results of these investigations have relevance to a wide group of reading researchers, should guide the approach to future investigations and should have practical relevance hi informing improved approaches to the intervention for, and perhaps, prevention of, learning disabilities in children.